@kitware/vtk.js/Rendering/OpenGL/CellArrayBufferObject/helpers.js

Visualization Toolkit for the Web

import { vec3, mat4, quat } from 'gl-matrix';

function computeCoordShiftAndScale(points) {
  // Find out if shift scale should be used
  // Compute squares of diagonal size and distance from the origin
  let diagSq = 0.0;
  let distSq = 0.0;
  for (let i = 0; i < 3; ++i) {
    const range = points.getRange(i);
    const delta = range[1] - range[0];
    diagSq += delta * delta;
    const distShift = 0.5 * (range[1] + range[0]);
    distSq += distShift * distShift;
  }
  const useShiftAndScale = diagSq > 0 && (Math.abs(distSq) / diagSq > 1.0e6 ||
  // If data is far from the origin relative to its size
  Math.abs(Math.log10(diagSq)) > 3.0 ||
  // If the size is huge when not far from the origin
  diagSq === 0 && distSq > 1.0e6); // If data is a point, but far from the origin

  if (useShiftAndScale) {
    // Compute shift and scale vectors
    const coordShift = new Float64Array(3);
    const coordScale = new Float64Array(3);
    for (let i = 0; i < 3; ++i) {
      const range = points.getRange(i);
      const delta = range[1] - range[0];
      coordShift[i] = 0.5 * (range[1] + range[0]);
      coordScale[i] = delta > 0 ? 1.0 / delta : 1.0;
    }
    return {
      useShiftAndScale,
      coordShift,
      coordScale
    };
  }
  return {
    useShiftAndScale,
    coordShift: new Float32Array([0, 0, 0]),
    coordScale: new Float32Array([1, 1, 1])
  };
}
function computeInverseShiftAndScaleMatrix(coordShift, coordScale) {
  const inverseScale = new Float64Array(3);
  vec3.inverse(inverseScale, coordScale);
  const matrix = new Float64Array(16);
  mat4.fromRotationTranslationScale(matrix, quat.create(), coordShift, inverseScale);
  return matrix;
}
var helpers = {
  computeCoordShiftAndScale,
  computeInverseShiftAndScaleMatrix
};

export { computeCoordShiftAndScale, computeInverseShiftAndScaleMatrix, helpers as default };